Process of increasing the strength of insolubilized artificial protein filaments



Patented May 2, 1950 PROCESS OF INCREASING THE STRENGTH F INSOLUBILIZED ARTIFICIAL PROTEIN FILAMENTS Robin H. K. Thomson, Kilwinning, and David Traill, Ardrossan, Scotland, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application July 26, 1945, Serial No. 607,271. In Great Britain September 6, 1944 7 Claims. (01. 8-1276) The present invention relates to the production of improved artificial insolubilised protein filaments of the kind wherein the insolubilisation of the coagulated filaments obtained by wet spinning is carried out by means of formalif the treatment is carried on for half an hour to dehyde in the presence of a strongly acidified three quarters of an hour, and there is no adsaline solution. vantage in prolonging the treatment unduly.

The invention is especially applicable to insolu- Depending on the alkalinity (pH) at which the bilised filaments produced from alkaline solutreatment is carried out there may be used mild tions of casein and alkaline solutions of vegeor strong alkalies or buffered strong alkalies. ta-ble'globulins, for instance, peanut globulin solu- The invention isillustrated by the following tions or soya bean globulin solutions in dilute example: sodium hydroxide solution. The invention has Example for an object to increase the strength of the insolubfli ed protein filaments A matured alkaline solution of peanut globulin The insolubilisation of the coagulated wet spun is p o a c agulating bath consisting of an protein filaments can be most efiectively or conaqueous Solution containing phuric acid veniently carried out by means of formaldehyde and sodium sulphate at 30 C. from which in the presence of a, strongly acidified aqueous it iS withdrawn at a linear rate exceeding the saline solution, which may advantageously be ac- 20 linear rate of its extrusion and the coagulated complished by the use of formaldehyde in assofilaments are stretched in a bath of the same elation with a concentrated aqueous solution of a comp s h y are h n Wound on to a saline halide acidified with hydrochloric or sul- Swift d sed in a saturated sodium chlophuric acid as described in British Patent 513,910. ride solution at for 1 i e after which w il t is knqwn th t stretching of t coagthey are cut into staple fibre form. The staple ulated wet spun filaments previous to their insolfibre is then e ed in twenty times its dry ubilisation has a beneficial effect on the strength Weight of an insolubilising bath s ng of a of the insolubilised filaments obtained from these, Solution Containing 2 ulphuric acid, 1.5% and that the strength of the insolubilised filaformaldehyde and 26% o um chloride for 20 ments can frequently be further increased by 30 hours at 40 C. The resulting insolubilised staple treatments involving further stretching, it is fi is e thoroughly ashed With Water and often inconvenient to stretch the filaments after s ed in an 0.06% solution of sodium cetyl sulthey have been insolubilised and the effects proph n h n in dium carbonate soluduced are usually only temporary. tion. It is then thoroughly washed in water and We have now found that a further improvedried at 100 C. The filaments in the re ul ment in the strength of the filaments obtained staple fibr hav an avera str n th of 7.7 from coagulated protein filaments that have kilogram p r square llimetre as measured on been insolubilised with formaldehyde in presthe Cliii au ogr phio recorder. They are pracence of strongly acidified saline solutions, and tioally u a ec in handle by treatment for 90 if desired washed to free them from salts and minutes at in a bath Containing uncombined acid or formaldehyde, is obtained Sulphuric acid and 0.25 p n od m Su if the insolubilised filaments are treated even in phate, and the bath liquor fails to give a p ithe relaxed condition with a strong aqueous formtive response to the so-called biuret test for proaldehyde solution having a pH between aptein degradation products. proximately 8.6 and 10.4, preferably between 9.0 The fiber is then immersed in 20 times its and 10.0. weight of 40 per cent formalin at room tempera- According to the present invention, therefore, ture to which has been added sufficient sodium the method for the production of improved artihydroxide to give the solution a pH of 9.6 as flcial insolubilised protein filaments of the kind measured on an electromatic pH meter and is herein defined comprises treating the insolubil- 5Q allowed to remain for 40 minutes in the soluised filaments with a strong aqueous formaldetion. The staple fibre is then removed and is hyde solution havingapI-I between approximately thoroughly washed with water and dried at 8.6 and 10.4, preferably between 9.0 and 10.0. 100 C- Wh n asu d on t C fi au aphi The time for which the treatment should be recorder its strength is now approximately 12 carried on will depend on a number of factors inkilograms per square millimetre. For the above cluding the temperature and the formaldehyde concentration, but with formaldehyde of commercial strength at room temperature brought to a pH of 8.6 to 10.4 excellent results are obtained 3 tensile strength measurements the staple fibre is brought into equilibrium with an atmosphere of 60 per cent relative humidity after it has been dried.

We claim:

1. The method for the production of protein filaments which comprises insolubilizing coagulated protein filaments by treatment with an acidic, saline solution of formaldehyde and;

thereafter, contacting the insolubilized-filaments.

for a time corresponding to about 30 to 45 minutes at room temperature with a formaldehyde solution of approximately 40% formaldehyde concentration having pH-rbetween about 8.6 and 10.4.

2. The method of claim 1 wherein said pH is between 9.0 and 10.0.

3. The method of claim 1 wherein said insolubilized filaments are contacted with: the formaldehyde treating solution by immersion in said solution in a relaxed condition. 7

4.- The method for the productionqof protein. filaments which comprises insolubilizin-g coagulated protein filaments by treatment with an acidic saline solution of formaldehyde, washing the insolubilized filaments in order tofree them from adhering acid and salts and, thereafter, contacting the insolubilized filaments for. a time corresponding toabout 30 110 45 minutes at room temperature with a form-aldehydesolution of approximately 40% formaldehyde concentration having a pH between about 8.6 and'10.4.

REFERENCES CITED The following references are of record in the file of this patentt" UNITED STATES PATENTS Number Name Date 2,312,998 Kadt Mar. 2, 1943 2,335,576 Borner Nov. 30, 1943 2,340,909 Traill et a1. Febr8, 1944 2,347,677 Fieldsend. et' 1. ;May 2, 1944 2,358,383 Chibnall et a1. Sept.'19, 1944 FOREIGN PATENTS Number Country Date 512,640 Great Britain Sept. 21, 1939 546,978 Great Britain Aug. 7, 1942 OTHER REFERENCES 7 Kate et al., J. Applied Chem. Us-SR.) 1943 1 134-42. Abst. in J. Text. Inst. July 1944, 15. A283. 

1. THE METHOD FOR THE PRODUCTION OF PROTEIN FILAMENTS WHICH COMPRISES INSOLUBILIZING COAGULATED PROTEIN FILAMENTS BY TREATMENT WITH AN ACIDIC, SALINE SOLUTION OF FORMALDEHYDE AND, THEREAFTER, CONTACTING THE INSOLUBILIZED FLAMENTS FOR A TIME CORRESPONDING TO ABOUT 30 TO 45 MINUTES AT ROOM TEMPERATURE WITH A FORMALDEHYDE SOLUTION OF APPROXIMATELY 40% FORMALDEHYDE CONCENTRATION HAVING A PH BETWEEN ABOUT 8.6 AND 10.4. 